I have done a few incremental nightly builds with CyanogenMod and twice after doing the upgrade, the phone first lost mobile data and after a second upgrade to undo the damage important phone processes like phone and media kept dying. The phone displays a popup alert constantly, rendering the phone unusable. I found this is the best way to recover your phone:

1. To reduce the popup alerts until you get home, turn on airplane mode. Though getting to Settings to turn it on will be difficult.
2. When you are able to, reboot your phone into recover mode and factory reset the phone. You will lose your phone’s data but you will get your phone back.

There are likely other ways to resolve this issue but this is a good one.